Method and System for Determining a Level of a Sanding Surface Preparation of a Carbon Fiber Composite Surface Prior to a Post-Processing Operation

ABSTRACT

There is provided a quantitative method for determining a level of a sanding surface preparation of a carbon fiber composite surface, prior to the carbon fiber composite surface undergoing a post-processing operation. The quantitative method includes fabricating a ladder panel of levels of sanding correlating to an amount of sanding of sanding surface preparation standards for a reference carbon fiber composite surface of reference carbon fiber composite structure(s); using surface analysis tools to create target values for quantifying the levels of sanding; measuring, with the surface analysis tools, sanding surface preparation location(s) on the carbon fiber composite surface of a test carbon fiber composite structure, to obtain test result measurement(s); comparing the test result measurement(s) to the levels, to obtain test result level(s); determining if the test result level(s) meet the target values; and determining whether the carbon fiber composite surface is acceptable to proceed with the post-processing operation.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a continuation application and claimspriority to pending application Ser. No. 16/274,184, filed Feb. 12,2019, Attorney Docket Number 18-0508-US-NP, the entire contents of whichis incorporated herein by reference.

REFERENCE TO GOVERNMENT CONTRACT

This invention was made with Government support under contract numberNNLO9AA00A NASA ACC 2C26 awarded by NASA. The government has certainrights in this invention.

BACKGROUND 1) Field of the Disclosure

The disclosure relates generally to methods and systems for processcontrol in the manufacture of composite structures, and moreparticularly, to methods and systems for process control of abrasivesurface preparation of composite structures, prior to undergoingpost-processing operations, such as bonding or painting.

2) Description of Related Art

High performance applications for bonded composite structures, such ascomposite panels made of carbon fiber epoxy composite material oranother suitable composite material, requires assurance of propersurface preparation prior to bonding. For example, proper surfacepreparation may include sanding of the composite surface prior tobonding, and verifying that the sanding occurred, and that the sandingwas performed correctly, to avoid over sanding or under sanding of thecomposite surface.

Known methods and systems exist for verifying proper surface preparationof sanded surfaces. However, such known methods and systems may rely oninspection of a visual characteristic such as gloss level, i.e., “glossremoved” assessment, of the sanded surface. Such visual inspection istypically subjective in nature and not quantitative, and may result ininconsistent and unreliable surface preparation and process control,such as bond process control, which may, in turn, affect the quality ofbonding of the composite surface to another structure.

Thus, it would be advantageous to have a method and a system that takeinto account one or more of the issues discussed above, that provide aquantitative method and system for ensuring consistent and reliableabrasive surface preparation for a composite surface, prior to thecomposite surface undergoing a post-processing operation, such asbonding or painting, that ensures the quality of subsequent adhesivebonding, and that provide advantages over known methods and systems.

SUMMARY

Example implementations of the present disclosure provide for methodsand a system for determining a quality of an abrasive surfacepreparation of a composite surface, prior to undergoing apost-processing operation, and that provide significant advantages overexisting methods and systems.

In one version there is provided a method for determining a quality ofan abrasive surface preparation of a composite surface, prior to thecomposite surface undergoing a post-processing operation. The methodcomprises fabricating a plurality of levels of abrasive surfacepreparation standards for a reference composite surface of one or morereference composite structures. The method further comprises using oneor more surface analysis tools to create one or more target values forquantifying each of the plurality of levels of the abrasive surfacepreparation standards.

The method further comprises measuring, with the one or more surfaceanalysis tools, one or more abrasive surface preparation locations onthe composite surface of a test composite structure, to obtain one ormore test result measurements. The method further comprises comparingeach of the one or more test result measurements to the plurality oflevels of the abrasive surface preparation standards, to obtain one ormore test result levels of the abrasive surface preparation of the testcomposite structure.

The method further comprises determining if the one or more test resultlevels of the abrasive surface preparation meet the one or more targetvalues, to determine the quality of the abrasive surface preparation ofthe composite surface. The method further comprises determining whetherthe composite surface of the test composite structure is acceptable toproceed with undergoing the post-processing operation.

In another version there is provided a quantitative method fordetermining a quality of a sanding surface preparation of a carbon fibercomposite surface, prior to bonding the carbon fiber composite surfaceto a structure. The quantitative method comprises fabricating aplurality of levels of sanding surface preparation standards for areference carbon fiber composite surface of one or more reference carbonfiber composite structures. The quantitative method further comprisesusing one or more surface analysis tools to create one or more targetvalues for quantifying each of the plurality of levels of the sandingsurface preparation standards, wherein the one or more surface analysistools comprise a Fourier transform infrared (FTIR) spectrometer, anoptically stimulated electron emission (OSEE) sensor, a gloss meter, acolorimeter, and an optical interferometer.

The quantitative method further comprises measuring, with the one ormore surface analysis tools, one or more sanding surface preparationlocations on the carbon fiber composite surface of a test carbon fibercomposite structure, to obtain one or more test result measurements. Thequantitative method further comprises comparing each of the one or moretest result measurements to the plurality of levels of the sandingsurface preparation standards, to obtain one or more test result levelsof the sanding surface preparation of the test carbon fiber compositestructure.

The quantitative method further comprises determining if the one or moretest result levels of the sanding surface preparation meet the one ormore target values, to determine the quality of the sanding surfacepreparation of the carbon fiber composite surface. The quantitativemethod further comprises determining whether the carbon fiber compositesurface of the test carbon fiber composite structure is acceptable toproceed with bonding to the structure.

In another version there is provided a system for determining a qualityof an abrasive surface preparation of a composite surface, prior to thecomposite surface undergoing a post-processing operation. The systemcomprises a reference composite structure having a reference compositesurface. The system further comprises a plurality of levels of abrasivesurface preparation standards fabricated for the reference compositesurface.

The system further comprises a test composite structure having thecomposite surface, and the composite surface having one or more abrasivesurface preparation locations that have been abraded with an abradingdevice. The system further comprises one or more surface analysis tools,to create one or more target values for quantifying each of theplurality of levels of the abrasive surface preparation standards. Theone or more surface analysis tools are configured to measure the one ormore abrasive surface preparation locations, to obtain one or more testresult measurements.

Each of the one or more test result measurements is compared to theplurality of levels of the abrasive surface preparation standards, toobtain one or more test result levels of the abrasive surfacepreparation of the test composite structure, and to determine if the oneor more test result levels meet the one or more target values, todetermine the quality of the abrasive surface preparation of thecomposite surface, and to determine if the composite surface isacceptable to proceed with undergoing the post-processing operation.

The features, functions, and advantages that have been discussed can beachieved independently in various embodiments of the disclosure or maybe combined in yet other embodiments further details of which can beseen with reference to the following description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure can be better understood with reference to the followingdetailed description taken in conjunction with the accompanying drawingswhich illustrate preferred and exemplary version, but which are notnecessarily drawn to scale, wherein:

FIG. 1 is an illustration of a flowchart of steps of an exemplaryversion of a method of the disclosure;

FIG. 2 is an illustration of a flowchart of steps of another exemplaryversion of a method of the disclosure;

FIG. 3 is an illustration of a functional block diagram showing anexemplary version of a system of the disclosure;

FIG. 4 is an illustration of an exemplary version of an in-line processcontrol check of the disclosure;

FIG. 5A is an illustration of a graph showing Fourier transform infrared(FTIR) spectra plots in a C—H bonding region of epoxy composite surfacesat various levels of sanding;

FIG. 5B is an illustration of a graph showing a Fourier transforminfrared (FTIR)C—H region peak area of epoxy composite surfaces aftersanding;

FIG. 6 is an illustration of a perspective side view of a Fouriertransform infrared (FTIR) spectrometer in use by a user taking Fouriertransform infrared (FTIR) signal be of an abraded surface of a compositestructure;

FIG. 7 is an illustration of a graph showing optically stimulatedelectron emission (OSEE) signal measurements of epoxy composite surfacesat various levels of sanding;

FIG. 8 is an illustration of a perspective side view of an opticallystimulated electron emission (OSEE) sensor in use by a user takingoptically stimulated electron emission (OSEE) signal measurements of anabraded surface of a composite structure;

FIG. 9 is an illustration of a graph showing gloss individual maximumsof epoxy composite surfaces at various levels of sanding;

FIG. 10 is an illustration of a perspective side view of a gloss meterin use by a user taking gloss measurements of an abraded surface of acomposite structure;

FIG. 11 is an illustration of a graph showing delta color valuesindividual maximums of epoxy composite surfaces at various levels ofsanding;

FIG. 12 is an illustration of a perspective top view of a colorimeter inuse by a user measuring color values of an abraded surface of acomposite structure;

FIG. 13 is an illustration of a graph showing a roughness measurementdistribution of epoxy composite surfaces at various levels of sanding;

FIG. 14 is an illustration of a perspective front view of an opticalinterferometer in operation to take roughness measurements of an abradedsurface of a composite structure;

FIG. 15 is an illustration of a graph of an exemplary bond process flowtime monitoring showing an out of process condition;

FIG. 16 is an illustration of a perspective view of an air vehicleincorporating one or more parts that may be manufactured using anexemplary version of an in-line process control check of the disclosure;

FIG. 17 is an illustration of a flow diagram of an exemplary aircraftmanufacturing and service method; and

FIG. 18 is an illustration of an exemplary block diagram of an aircraft.

The figures shown in this disclosure represent various aspects of theembodiments presented, and only differences will be discussed in detail.

DETAILED DESCRIPTION

Disclosed versions or embodiments will now be described more fullyhereinafter with reference to the accompanying drawings, in which some,but not all of the disclosed versions are shown. Indeed, severaldifferent versions may be provided and should not be construed aslimited to the versions set forth herein. Rather, these versions areprovided so that this disclosure will be thorough and fully convey thescope of the disclosure to those skilled in the art.

Now referring to the Figures, FIG. 1 is an illustration of a flowchartof steps of an exemplary version of a method 10 of the disclosure, FIG.2 is an illustration of a flowchart of steps of an exemplary version ofa quantitative method 10 a of the disclosure, and FIG. 3 is anillustration of a functional block diagram showing an exemplary versionof a system 90 of the disclosure.

The blocks in FIGS. 1-3 represent operations and/or portions thereof, orelements, and lines connecting the various blocks do not imply anyparticular order or dependency of the operations or portions thereof, orelements. FIGS. 1 and 2 and the disclosure of the steps of the method 10and the quantitative method 10 a, respectively, set forth herein shouldnot be interpreted as necessarily determining a sequence in which thesteps are to be performed. Rather, although one illustrative order isindicated, it is to be understood that the sequence of the steps may bemodified when appropriate. Accordingly, certain operations may beperformed in a different order or simultaneously.

As shown in FIG. 1 , in one version, there is provided the method 10 fordetermining a quality 24 (see FIG. 3 ) of an abrasive surfacepreparation 42 (see FIG. 3 ) of a composite surface 26 (see FIG. 3 ),prior to the composite surface 26 undergoing a post-processing operation50 (see FIG. 3 ). The abrasive surface preparation 42 may comprise asanding surface preparation 42 a (see FIG. 3 ), a grit blasting surfacepreparation, a nylon pad abrasive surface preparation, or anothersuitable abrasive surface preparation with an abrasive media tool thatphysically abrades the composite surface 26. As shown in FIG. 1 , themethod 10 comprises step 12 of fabricating a plurality of levels 55 (seeFIG. 3 ) of abrasive surface preparation standards 46 (see FIG. 3 ) fora reference composite surface 30 (see FIG. 3 ) of one or more referencecomposite structures 32 (see FIG. 3 ).

As shown in FIG. 1 , the method 10 further comprises step 14 of usingone or more surface analysis tools 60 (see FIG. 3 ), to create one ormore target values 62 (see FIG. 3 ) for quantifying each of theplurality of levels 55 of the abrasive surface preparation standards 46.As shown in FIG. 1 , the method 10 further comprises step 16 ofmeasuring, with the one or more surface analysis tools 60, one or moreabrasive surface preparation locations 44 (see FIG. 3 ) on the compositesurface 26 (see FIG. 3 ) of a test composite structure 28 a (see FIG. 3), to obtain one or more test result measurements 64 a (see FIG. 3 ).

The test composite structure 28 a and the one or more referencecomposite structures 32 may comprise a composite substrate 34 (see FIG.3 ), such as in the form of a composite panel 34 a (see FIG. 3 ), forexample, a carbon fiber epoxy composite panel 34 b (see FIG. 3 ), oranother suitable type of composite panel 34 a. The test compositestructure 28 a and the one or more reference composite structures 32 arepreferably made of a composite material 36 (see FIG. 3 ), for example, acarbon fiber epoxy composite material 36 a (see FIG. 3 ), or anothersuitable type of composite material 36. As shown in FIG. 3 , the testcomposite structure 28 a and the one or more reference compositestructures 32 may be fabricated or manufactured with a compositestructure fabrication 94.

The step 16 (see FIG. 1 ) of measuring, with the one or more surfaceanalysis tools 60, preferably comprises measuring one or more abrasivesurface preparation locations 44 on the composite surface 26 of the testcomposite structure 28 a, where the test composite structure 28 acomprises a carbon fiber epoxy composite panel 34 b (see FIG. 3 ).

The step 16 (see FIG. 1 ) of measuring, with the one or more surfaceanalysis tools 60, may further comprise measuring with the surfaceanalysis tool 60 comprising a Fourier transform infrared (FTIR)spectrometer 66 (see FIG. 3 ), to measure one or more Fourier transforminfrared (FTIR) signal measurements 67 (see FIG. 3 ) of the abrasivesurface preparation location(s) 44 of the composite surface 26. TheFourier transform infrared (FTIR) spectrometer 66 uses a Fouriertransform infrared (FTIR) spectroscopy process 68 (see FIG. 3 ) toobtain an infrared (IR) spectra of absorption or emission of theabrasive surface preparation location(s) 44 of the composite surface 26of the test composite structure 28 a. The FTIR spectroscopy process 68preferably exposes the abrasive surface preparation locations(s) 44 ofthe composite surface 26 to an infrared (IR) light source that isreflected onto a detector, which precisely measures the amount of lightabsorbed by the abrasive surface preparation location 44 of thecomposite surface 26. The FTIR spectrometer 66 is able to detect a testresult level 58 of the abrasive surface preparation 42, including acomposite surface treatment 102 (see FIG. 4 ), of the test compositestructure 28 a. The FTIR spectroscopy process 68 may further require apost signal processing 69 (see FIG. 3 ).

The step 16 (see FIG. 1 ) of measuring, with the one or more surfaceanalysis tools 60, may further comprise measuring with the surfaceanalysis tool 60 comprising an optically stimulated electron emission(OSEE) sensor 70, to measure one or more optically stimulated electronemission (OSEE) signal measurements 72, of the abrasive surfacepreparation location(s) 44 of the composite surface 26. The OSEE sensor70 uses ultraviolet (UV) light to create electron emission from theabrasive surface preparation location(s) 44 of the composite surface 26,resulting in a small current detected by the OSEE sensor 70. The OSEEsensor 70 may require a compressed gas 73 (see FIG. 3 ), such as acompressed argon gas 73 a (see FIG. 3 ), to function.

The step 16 (see FIG. 1 ) of measuring, with the one or more surfaceanalysis tools 60, may further comprise measuring with the surfaceanalysis tool 60 comprising a gloss meter 74, to measure one or moregloss measurements 76 of gloss 77 at one or more gloss illuminationangle geometries 78 of the abrasive surface preparation location(s) 44of the composite surface 26. The gloss illumination angle geometries 78may comprise an 85 (eighty-five) degree gloss illumination anglegeometry 78 a (see FIG. 3 ), a 60 (sixty) degree gloss illuminationangle geometry 78 b (see FIG. 3 ), a 20 (twenty) degree glossillumination angle geometry 78 c (see FIG. 3 ), or another suitablegloss illumination angle geometry 78. Preferably, the gloss meter 74measures the one or more gloss measurements 76 of gloss 77 at the glossillumination angle geometry 78 comprising the 85 (eighty-five) degreegloss illumination angle geometry 78 a. The gloss meter 74 measuring thegloss measurement 76 of gloss 77 at the 85 (eighty-five) degree glossillumination angle geometry 78 a is able to detect the test result level58 of the abrasive surface preparation 42 of the test compositestructure 28 a.

The step 16 (see FIG. 1 ) of measuring, with the one or more surfaceanalysis tools 60, may further comprise measuring with the surfaceanalysis tool 60 comprising a colorimeter 80 (see FIG. 3 ), to measurecolor 85 (see FIG. 3 ), such as one or more color values 82 (see FIG. 3), including one or more delta color values 84 (see FIG. 3 ), forexample, a delta E* (ΔE*) color value 84 a (see FIG. 3 ) and a delta L*(ΔL*) color value 84 b (see FIG. 3 ), of the abrasive surfacepreparation location(s) 44 of the composite surface 26. The colorimeter80 measuring the delta color values 84 of the delta E* (ΔE*) color value84 a and the delta L* (ΔL*) color value 84 b is able to detect the testresult level 58 of the abrasive surface preparation 42 of the testcomposite structure 28 a.

The step 16 (see FIG. 1 ) of measuring, with the one or more surfaceanalysis tools 60, may further comprise measuring with the surfaceanalysis tool 60 comprising an optical interferometer 86, to measure oneor more roughness measurements 87 of roughness 88 of the abrasivesurface preparation location(s) 44 of the composite surface 26. Theroughness 88 is preferably an arithmetical mean roughness (Ra) 88 a (seeFIG. 3 ) and a mean roughness depth (Rz) 88 b (see FIG. 3 ). The opticalinterferometer 86 measuring the roughness measurements 87 is able todetect the test result level 58 of the abrasive surface preparation 42,including the composite surface treatment 102 (see FIG. 4 ), of the testcomposite structure 28 a.

As shown in FIG. 1 , the method 10 further comprises step 18 ofcomparing each of the one or more test result measurements 64 a to theplurality of levels 55 of the abrasive surface preparation standards 46,to obtain the one or more test result levels 58 (see FIG. 3 ) of theabrasive surface preparation 42, of the test composite structure 28 a.

As shown in FIG. 1 , the method 10 further comprises step 20 ofdetermining if the one or more test result levels 58 of the abrasivesurface preparation 42 meet the one or more target values 62, todetermine the quality 24 (see FIG. 3 ) of the abrasive surfacepreparation 42 of the composite surface 26. Preferably, a Fouriertransform infrared (FTIR) target value 62 a (see FIG. 3 ) comprises apeak area under a curve that is less than 7 (seven) for measuring acomposite surface 26, such as an epoxy composite surface 26 c (see FIG.3 ). Preferably, an optically stimulated electron emission (OSEE) targetvalue 62 b (see FIG. 3 ) comprises an optically stimulated electronemission (OSEE) signal measurement 72 of about 100 (one hundred) formeasuring a composite surface 26, such as an epoxy composite surface 26c (see FIG. 3 ).

Preferably, a gloss target value 62 c (see FIG. 3 ) for the 85(eighty-five) degree gloss illumination angle geometry 78 a is less than12 (twelve) for measuring a composite surface 26, such as an epoxycomposite surface 26 c (see FIG. 3 ). Preferably, a color target value62 d (see FIG. 3 ) for the delta E* (ΔE*) color value 84 a (see FIG. 3 )is as close to 0 (zero) as possible for measuring a composite surface26, such as an epoxy composite surface 26 c (see FIG. 3 ). Preferably, aroughness target value 62 e (see FIG. 3 ) using the opticalinterferometer 86 comprises a correlation coefficient greater than 98%(ninety-eight percent) for measuring a composite surface 26, such as anepoxy composite surface 26 c (see FIG. 3 ).

As shown in FIG. 1 , the method 10 further comprises step 22 ofdetermining whether the composite surface 26 of the test compositestructure 28 a is acceptable to proceed with undergoing thepost-processing operation 50 (see FIG. 3 ). The step 22 of determiningwhether the composite surface 26 of the test composite structure 28 a isacceptable to proceed with undergoing the post-processing operation 50may comprise determining whether the composite surface 26 is acceptableto proceed with undergoing the post-processing operation 50 comprisingbonding 52 (see FIG. 3 ) the composite surface 26 to a structure 40 (seeFIG. 3 ). The bonding 52 may include paste bonding 52 a (see FIG. 3 ),adhesive bonding 52 b (see FIG. 3 ), or another suitable type of bonding52, of the composite surface 26 to the structure 40. The structure 40may comprise an aircraft structure 40 a or another suitable structure40.

Alternatively, the step 22 of determining whether the composite surface26 of the test composite structure 28 a is acceptable to proceed withundergoing the post-processing operation 50 may comprises determiningwhether the composite surface 26 is acceptable to proceed withundergoing the post-processing operation 50 comprising painting 53 (seeFIG. 3 ) the composite surface 26 with a paint 54 (see FIG. 3 ).

In another version, there is provided the quantitative method 10 a (seeFIG. 2 ) for determining a quality 24 (see FIG. 3 ) of a sanding surfacepreparation 42 a (see FIG. 3 ) of a carbon fiber composite surface 26 b(see FIG. 3 ), prior to bonding 52 (see FIG. 3 ) the carbon fibercomposite surface 26 b to a structure 40 (see FIG. 3 ), such as anaircraft structure 40 a (see FIG. 3 ). As shown in FIG. 2 , thequantitative method 10 a comprises step 12 a of fabricating a pluralityof levels 55 (see FIG. 3 ) of sanding surface preparation standards 46 a(see FIG. 3 ) for a reference carbon fiber composite surface 30 a (seeFIG. 3 ) of one or more reference carbon fiber composite structures 32 a(see FIG. 3 ).

As shown in FIG. 2 , the quantitative method 10 a further comprises step14 a of using one or more surface analysis tools 60 (see FIG. 3 ) tocreate one or more target values 62 (see FIG. 3) for quantifying each ofthe plurality of levels 55 (see FIG. 3 ) of the sanding surfacepreparation standards 46 a (see FIG. 3 ). The one or more surfaceanalysis tools 60 preferably comprise a Fourier transform infrared(FTIR) spectrometer 66 (see FIG. 3 ), an optically stimulated electronemission (OSEE) sensor 70 (see FIG. 3 ), a gloss meter 74 (see FIG. 3 ),a colorimeter 80 (see FIG. 3 ), and an optical interferometer 86 (seeFIG. 3 ).

As shown in FIG. 2 , the quantitative method 10 a further comprises step16 a of measuring, with the one or more surface analysis tools 60, oneor more sanding surface preparation locations 44 a (see FIG. 3 ) on thecarbon fiber composite surface 26 b (see FIG. 3 ) of a test carbon fibercomposite structure 28 b (see FIG. 3 ), to obtain one or more testresult measurements 64 a (see FIG. 3 ).

The step 16 a (see FIG. 2 ) of measuring, with the one or more surfaceanalysis tools 60, may further comprise measuring with the surfaceanalysis tool 60 comprising the FTIR spectrometer 66, to measure one ormore Fourier transform infrared (FTIR) signal measurements 67 (see FIG.3 ), of the sanding surface preparation location(s) 44 a of the carbonfiber composite surface 26 b. The FTIR spectrometer 66 uses the Fouriertransform infrared (FTIR) spectroscopy process 68 to obtain the infrared(IR) spectra of absorption or emission of the sanding surfacepreparation location(s) 44 a of the carbon fiber composite surface 26 bof the test carbon fiber composite structure 28 b. The FTIR spectroscopyprocess 68 preferably exposes the sanding surface preparationlocation(s) 44 a of the carbon fiber composite surface 26 b to theinfrared (IR) light source that is reflected onto a detector, whichprecisely measures the amount of light absorbed by the sanding surfacepreparation location 44 a of the carbon fiber composite surface 26 b.The FTIR spectrometer 66 is able to detect the test result level 58 ofthe sanding surface preparation 42 a, including the composite surfacetreatment 102 (see FIG. 4 ), of the test carbon fiber compositestructure 28 b. The FTIR spectroscopy process 68 may further require thepost signal processing 69 (see FIG. 3 ).

The step 16 a (see FIG. 2 ) of measuring, with the one or more surfaceanalysis tools 60, may further comprise measuring with the surfaceanalysis tool 60 comprising the OSEE sensor 70, to measure one or moreoptically stimulated electron emission (OSEE) signal measurements 72 ofthe sanding surface preparation location(s) 44 a of the carbon fibercomposite surface 26 b. The OSEE sensor 70 uses ultraviolet (UV) lightto create electron emission from the sanding surface preparationlocation(s) 44 a of the carbon fiber composite surface 26 b, resultingin a small current detected by the OSEE sensor 70. The OSEE sensor 70may require compressed gas 73 (see FIG. 3 ), such as compressed argongas 73 a (see FIG. 3 ), to function.

The step 16 a (see FIG. 2 ) of measuring, with the one or more surfaceanalysis tools 60, may further comprise measuring with the surfaceanalysis tool 60 comprising the gloss meter 74, to measure one or moregloss measurements 76 of gloss 77 at one or more gloss illuminationangle geometries 78 of the sanding surface preparation location(s) 44 aof the carbon fiber composite surface 26 b. The gloss illumination anglegeometries 78 may comprise the 85 (eighty-five) degree glossillumination angle geometry 78 a (see FIG. 3 ), the 60 (sixty) degreegloss illumination angle geometry 78 b (see FIG. 3 ), the 20 (twenty)degree gloss illumination angle geometry 78 c (see FIG. 3 ), or anothersuitable gloss illumination angle geometry 78. Preferably, the glossmeter 74 measures the one or more gloss measurements 76 of gloss 77 atthe gloss illumination angle geometry 78 comprising the 85 (eighty-five)degree gloss illumination angle geometry 78 a. The gloss meter 74measuring the gloss measurement 76 of gloss 77 at the 85 (eighty-five)degree gloss illumination angle geometry 78 a is able to detect the testresult level 58 of the sanding surface preparation 42 a of the testcarbon fiber composite structure 28 b.

The step 16 a (see FIG. 2 ) of measuring, with the one or more surfaceanalysis tools 60, may further comprise measuring with the surfaceanalysis tool 60 comprising the colorimeter 80 (see FIG. 3 ), to measurecolor 85 (see FIG. 3 ), such as one or more color values 82 (see FIG. 3), including one or more delta color values 84 (see FIG. 3 ), forexample, the delta E* (ΔE*) color value 84 a (see FIG. 3 ) and the deltaL* (ΔL*) color value 84 b (see FIG. 3 ), of the sanding surfacepreparation location(s) 44 a of the carbon fiber composite surface 26 b.The colorimeter 80 measuring the delta color values 84 of the delta E*(ΔE*) color value 84 a and the delta L* (ΔL*) color value 84 b is ableto detect the test result level 58 of the sanding surface preparation 42a of the test carbon fiber composite structure 28 b.

The step 16 a (see FIG. 2 ) of measuring, with the one or more surfaceanalysis tools 60, may further comprise measuring with the surfaceanalysis tool 60 comprising the optical interferometer 86, to measureone or more roughness measurements 87 of roughness 88 of the sandingsurface preparation location(s) 44 a of the carbon fiber compositesurface 26 b. The roughness 88 is preferably the arithmetical meanroughness (Ra) 88 a (see FIG. 3 ) and the mean roughness depth (Rz) 88 b(see FIG. 3 ). The optical interferometer 86 measuring the roughnessmeasurements 87 is able to detect the test result level 58 of thesanding surface preparation 42 a, including the composite surfacetreatment 102 (see FIG. 4 ), of the test carbon fiber compositestructure 28 b.

As shown in FIG. 2 , the quantitative method 10 a further comprises step18 a of comparing each of the one or more test result measurements 64 a(see FIG. 3 ) to the plurality of levels 55 (see FIG. 3 ) of the sandingsurface preparation standards 46 a, to obtain one or more test resultlevels 58 (see FIG. 3 ) of the sanding surface preparation 42 a (seeFIG. 3 ) of the test carbon fiber composite structure 28 b.

As shown in FIG. 2 , the quantitative method 10 a further comprises step20 a of determining if the one or more test result levels 58 of thesanding surface preparation 42 a meet the one or more target values 62,to determine the quality 24 (see FIG. 3 ) of the sanding surfacepreparation 42 a of the carbon fiber composite surface 26 b. Asdiscussed above, preferably, the FTIR target value 62 a (see FIG. 3 )comprises the peak area under a curve that is less than 7 (seven) formeasuring a carbon fiber composite surface 26 b, such as an epoxycomposite surface 26 c (see FIG. 3 ). Preferably, the OSEE target value62 b (see FIG. 3 ) comprises the OSEE signal measurement 72 of about 100(one hundred) for measuring the carbon fiber composite surface 26 b,such as the epoxy composite surface 26 c (see FIG. 3 ).

Preferably, the gloss target value 62 c (see FIG. 3 ) for the 85(eighty-five) degree gloss illumination angle geometry 78 a is less than12 (twelve) for measuring the carbon fiber composite surface 26 b, suchas the epoxy composite surface 26 c (see FIG. 3 ). Preferably, the colortarget value 62 d (see FIG. 3 ) for the delta E* (ΔE*) color value 84 a(see FIG. 3 ) is as close to 0 (zero) as possible for measuring thecarbon fiber composite surface 26 b, such as the epoxy composite surface26 c (see FIG. 3 ). Preferably, the roughness target value 62 e (seeFIG. 3 ) using the optical interferometer 86 comprises the correlationcoefficient greater than 98% (ninety-eight percent) for measuring thecarbon fiber composite surface 26 b, such as the epoxy composite surface26 c (see FIG. 3 ).

As shown in FIG. 2 , the quantitative method 10 a further comprises step22 a of determining whether the carbon fiber composite surface 26 b ofthe test carbon fiber composite structure 28 b is acceptable to proceedwith bonding 52 (see FIG. 3 ) to the structure 40 (see FIG. 3 ). Thebonding 52 may include paste bonding 52 a (see FIG. 3 ), adhesivebonding 52 b (see FIG. 3), or another suitable type of bonding 52, ofthe composite surface 26 to the structure 40. The structure 40 maycomprise an aircraft structure 40 a or another suitable structure 40.

FIG. 3 shows an exemplary version of the system 90 of the disclosure. Inanother version, there is provided the system 90 for determining thequality 24 (see FIG. 3 ) of the abrasive surface preparation 42 (seeFIG. 3 ), such as the sanding surface preparation 42 a (see FIG. 3 ), ofthe composite surface 26 (see FIG. 3 ), prior to the composite surface26 undergoing the post-processing operation 50 (see FIG. 3 ). Theabrasive surface preparation 42 may comprise the sanding surfacepreparation 42 a (see FIG. 3 ), a grit blasting surface preparation, anylon pad abrasive surface preparation, or another suitable abrasivesurface preparation with an abrasive media tool that physically abradesthe composite surface 26. The post-processing operation 50 may comprisebonding 52 (see FIG. 3 ) to a structure 40 (see FIG. 3 ), such as anaircraft structure 40 a (see FIG. 3 ). As shown in FIG. 3 , the bonding52 may comprise paste bonding 52 a (see FIG. 3 ), adhesive bonding 52 b(see FIG. 3 ), or another suitable type of bonding 52. As further shownin FIG. 3 , the post-processing operation 50 may comprise painting 53the composite surface 26 with paint 54.

As shown in FIG. 3 , the system 90 preferably comprises a processcontrol system (PCS) 90 a, such as a bond process control system (PCS)90 b. As further shown in FIG. 3 , the system 90 is preferably a realtime (RT) process control system (PCS) 90 c, and preferably the system90 is automated for bond process control. As further shown in FIG. 3 ,the system 90 is preferably used in an in-line process control check 92or monitoring.

As further shown in FIG. 3 , the system 90 comprises a referencecomposite structure 32, such as a reference carbon fiber compositestructure 32 a, having a reference composite surface 30, such as areference carbon fiber composite surface 30 a.

As further shown in FIG. 3 , the system 90 comprises a compositestructure 28, such as a test composite structure 28 a, for example, atest carbon fiber composite structure 28 b. The composite structure 28,such as the test composite structure 28 a, has the composite surface 26(see FIG. 3 ), such as a test composite surface 26 a (see FIG. 3 ). Thecomposite surface 26, such as the test composite surface 26 a, maycomprise a carbon fiber composite surface 26 b (see FIG. 3 ), such as anepoxy composite surface 26 c (see FIG. 3 ), or another suitable type ofcomposite surface 26.

The composite structure 28, such as the test composite structure 28 a,and the reference composite structure 32 may comprise a compositesubstrate 34 (see FIG. 3 ), such as in the form of a composite panel 34a (see FIG. 3 ), for example, a carbon fiber epoxy composite panel 34 b(see FIG. 3 ), or another suitable type of composite panel 34 a. Thecomposite structure 28, such as the test composite structure 28 a, andthe reference composite structure 32 may comprise an aircraft compositestructure 38 (see FIG. 3 ), or another suitable type of compositestructure 28, that may be bonded or painted. Further, the compositestructure 28, such as the test composite structure 28 a, and thereference composite structure 32 are preferably made of a compositematerial 36 (see FIG. 3 ), for example, a carbon fiber epoxy compositematerial 36 a (see FIG. 3 ), or another suitable type of compositematerial 36. As shown in FIG. 3 , the composite structure 28, such asthe test composite structure 28 a, and the reference composite structure32 may be fabricated or manufactured with a composite structurefabrication 94.

The system 90 further comprises a plurality of levels 55 (see FIG. 3 )of abrasive surface preparation standards 46 (see FIG. 3 ), such assanding surface preparation standards 46 a (see FIG. 3 ), fabricated forthe reference composite surface 30. For assessment of the surfaceanalysis tools 60 comprising the Fourier transform infrared (FTIR)spectrometer 66 (see FIG. 3 ), the optically stimulated electronemission (OSEE) sensor 70 (see FIG. 3 ), and the optical interferometer86 (see FIG. 3 ), the plurality of levels 55 preferably comprise levels56 (see FIG. 3 ) of the amount of abrading 48 (see FIG. 3 ), such assanding 48 a (see FIG. 3 ). As shown in FIGS. 6, 8, and 13 , anddiscussed in further detail below, the levels 56 of the amount ofabrading 48, such as sanding 48 a, include none (no sanding) 56 a, veryvery light 56 b, very light 56 c, light 56 d, medium light 56 e,semi-full 56 f, and full 56 g, and may also be referred to as a ladderpanel of the levels 56. For assessment of the surface analysis tools 60comprising the gloss meter 74 (see FIG. 3 ) and the colorimeter 80 (seeFIG. 3 ), the plurality of levels 55 preferably comprise levels 57 (seeFIG. 3 ) of the time of abrading 48 (see FIG. 3 ), such as sanding 48 a(see FIG. 3 ). As shown in FIGS. 9 and 11 , and as discussed in furtherdetail below, the levels 57 of the time of abrading 48, such as sanding48 a, include none (no sanding) 57 a, 5-10 seconds 57 b, 10-20 second 57c, 30 seconds 57 d, and 1 minute (baseline) 57 e.

The composite surface 26 of the test composite structure 28 a and thereference composite surface 30 of the reference composite structure 32may both undergo a composite surface treatment 102, such as the abrasivesurface preparation 42, for example, sanding surface preparation 42 a,using an abrading device 104 (see FIG. 3 ), such as a random orbitalsander (ROS) 104 a (see FIG. 3 ), or another suitable abrading device104, to obtain an abraded surface 49 (see FIG. 3 ), such as a sandedsurface 49 a (see FIG. 3 ). The composite surface 26 has one or moreabrasive surface preparation locations 44, such as sanding surfacepreparation locations 44 a (see FIG. 3 ), that have undergone abrading48 (see FIG. 3 ), such as sanding 48 a (see FIG. 3 ), for example,manual sanding 48 b (see FIG. 3 ), with the abrading device 104, such asthe random orbital sander (ROS) 104 a, or another suitable abradingdevice 104.

As shown in FIG. 3 , the system 90 further comprises one or more surfaceanalysis tools 60, such as portable surface analysis tools 60 a, thatare used for a composite surface measurement process check 106 (see FIG.3 ). The one or more surface analysis tools 60 are used to create one ormore target values 62 (see FIG. 3 ) for quantifying each of theplurality of levels 55 of the abrasive surface preparation standards 46.The one or more surface analysis tools 60 are configured to measure theone or more abrasive surface preparation locations 44, to obtain one ormore measurements 64 (see FIG. 3 ), such as one or more test resultmeasurements 64 a (see FIG. 3 ).

Each of the one or more measurements 64, such as the one or more testresult measurements 64 a, is compared to the plurality of levels 55 ofthe abrasive surface preparation standards 46, to obtain one or moretest result levels 58 (see FIG. 3 ) of the abrasive surface preparation42 of the composite structure 28, such as the test composite structure28 a, and to determine if the one or more test result levels 58 meet theone or more target values 62, to determine the quality 24 of theabrasive surface preparation 42 of the composite surface 26, and todetermine if the composite surface 26 is acceptable to proceed withundergoing the post-processing operation 50.

As shown in FIG. 3 , the surface analysis tool 60 may comprise theFourier transform infrared (FTIR) spectrometer 66, to measure one ormore Fourier transform infrared (FTIR) signal measurements 67 of thecomposite surface 26. As discussed above, the FTIR spectrometer 66 usesthe Fourier transform infrared (FTIR) spectroscopy process 68 (see FIG.3 ) to obtain the infrared (IR) spectra of absorption or emission of theabrasive surface preparation location(s) 44, such as the sanding surfacepreparation location(s) 44 a, of the composite surface 26 of the testcomposite structure 28 a. The FTIR spectrometer 66 is able to detect thetest result level 58 of the abrasive surface preparation 42, such as thesanding surface preparation 42 a, including the composite surfacetreatment 102, of the test composite structure 28 a. Preferably, theFourier transform infrared (FTIR) target value (TV) 62 a (see FIG. 3 )comprises a peak area under a curve that is less than 7 (seven) formeasuring the composite surface 26, such as the epoxy composite surface26 c (see FIG. 3 ). The FTIR spectroscopy process 68 may further requirethe post signal processing 69 (see FIG. 3 ).

As shown in FIG. 3 , the surface analysis tool 60 may further comprisethe optically stimulated electron emission (OSEE) sensor 70, to measureone or more optically stimulated electron emission (OSEE) signalmeasurements 72 of the abrasive surface preparation location(s) 44, suchas the sanding surface preparation location(s) 44 a, of the compositesurface 26 of the test composite structure 28 a. As discussed above, theOSEE sensor 70 uses ultraviolet (UV) light to create electron emissionfrom the abrasive surface preparation location(s) 44, such as thesanding surface preparation location(s) 44 a, of the composite surface26, resulting in a small current detected by the OSEE sensor 70.Preferably, the optically stimulated electron emission (OSEE) targetvalue (TV) 62 b (see FIG. 3 ) comprises the OSEE signal measurement 72of about 100 (one hundred) for measuring the composite surface 26, suchas the epoxy composite surface 26 c (see FIG. 3 ). The OSEE sensor 70may require compressed gas 73 (see FIG. 3 ), such as compressed argongas 73 a (see FIG. 3 ), to function.

As shown in FIG. 3 , the surface analysis tool 60 may further comprisethe gloss meter 74, to measure one or more gloss measurements 76 ofgloss 77 at one or more gloss illumination angle geometries 78 of theabrasive surface preparation location(s) 44, such as the sanding surfacepreparation location(s) 44 a, of the composite surface 26 of the testcomposite structure 28 a. As further shown in FIG. 3 , the glossillumination angle geometries 78 may comprise the 85 (eighty-five)degree gloss illumination angle geometry 78 a, the 60 (sixty) degreegloss illumination angle geometry 78 b, the 20 (twenty) degree glossillumination angle geometry 78 c, or another suitable gloss illuminationangle geometry 78. Preferably, the gloss meter 74 measures the one ormore gloss measurements 76 of gloss 77 at the gloss illumination anglegeometry 78 comprising the 85 (eighty-five) degree gloss illuminationangle geometry 78 a. Preferably, the gloss target value (TV) 62 c (seeFIG. 3 ) for the 85 (eighty-five) degree gloss illumination anglegeometry 78 a is less than 12 (twelve) for measuring the compositesurface 26, such as the epoxy composite surface 26 c (see FIG. 3 ).

As shown in FIG. 3 , the surface analysis tool 60 may further comprisethe colorimeter 80, to measure color 85 (see FIG. 3 ), such as one ormore color values (CV) 82, including one or more delta color values (CV)84, for example, the delta E* (ΔE*) color value 84 a and the delta L*(ΔL*) color value 84 b, of the abrasive surface preparation location(s)44, such as the sanding surface preparation location(s) 44 a, of thecomposite surface 26 of the test composite structure 28 a. Preferably,the color target value (TV) 62 d (see FIG. 3 ) for the delta E* (ΔE*)color value 84 a (see FIG. 3 ) is as close to 0 (zero) as possible formeasuring the composite surface 26, such as the epoxy composite surface26 c (see FIG. 3 ).

As shown in FIG. 3 , the surface analysis tool 60 may further comprisethe optical interferometer 86, to measure one or more roughnessmeasurements 87 of roughness 88 of the abrasive surface preparationlocation(s) 44, such as the sanding surface preparation location(s) 44a, of the composite surface 26 of the test composite structure 28 a. Theroughness 88 is preferably the arithmetical mean roughness (Ra) 88 a(see FIG. 3 ) and the mean roughness depth (Rz) 88 b (see FIG. 3 ).Preferably, the roughness target value (TV) 62 e (see FIG. 3 ) using theoptical interferometer 86 comprises a correlation coefficient greaterthan 98% (ninety-eight percent) for measuring the composite surface 26,such as the epoxy composite surface 26 c (see FIG. 3 ).

Now referring to FIG. 4 , FIG. 4 is an illustration of an exemplaryversion of the in-line process control check 92 (see also FIG. 3 ) ofthe disclosure. As shown in FIG. 4 , the exemplary in-line processcontrol check 92 comprises the composite structure fabrication 94 of thecomposite substrate 34, such as in the form of the composite panel 34 a,for example, a carbon fiber epoxy composite panel 34 b (see FIG. 3 ).However, the composite substrate 34 may be fabricated with any suitablecomposite material 36 (see FIG. 3 ).

As shown in FIG. 4 , the exemplary in-line process control check 92further comprises a composite surface preparation 96, such as a firstcomposite surface preparation 96 a, of the composite surface 26 (seeFIG. 3 ) of the composite substrate 34, such as the composite panel 34a. The composite surface preparation 96, such as the first compositesurface preparation 96 a, may comprise cleaning 98 (see FIG. 4 ), suchas a solvent wipe 100 (see FIG. 4 ), of the composite surface 26. Thecleaning 98 may be performed using a cloth or other suitable cleaningmaterial. The solvent wipe 100 may include wiping with a solvent such asa methyl propyl ketone/methyl isobutyl ketone mixture, or anothersuitable solvent or solvent mixture.

As shown in FIG. 4 , after the composite surface 26 is initiallycleaned, the exemplary in-line process control check 92 furthercomprises the composite surface treatment 102 of the composite surface26 (see FIG. 3 ) of the composite substrate 34, such as the compositepanel 34 a. The composite surface treatment 102 preferably comprisesabrading 48 (see FIG. 4 ), such as sanding 48 a (see FIG. 4 ), with anabrading device 104 (see FIG. 3 ), such as a random orbital sander (ROS)104 a (see FIG. 4 ). Preferably, manual sanding 48 b (see FIG. 3 ) ofthe composite surface 26 is performed. Several parameters may controlthe level 55 (see FIG. 3 ) of abrading 48, such as sanding 48 a,including pressure, disk speed (revolutions per minute (RPM)), number ofpasses, and overall time of abrading 48, such as sanding 48 a. Theabrading device 104, such as the random orbital sander (ROS) 104 a mayuse 180 grit aluminum oxide sand paper disks, or another suitable typeof sanding material.

As shown in FIG. 4 , after the composite surface 26 undergoes thecomposite surface treatment 102, the exemplary in-line process controlcheck 92 may further optionally comprise another composite surfacepreparation 96, such as a second composite surface preparation 96 b, asneeded, of the composite surface 26 (see FIG. 3 ), that has been abradedor sanded. The composite surface preparation 96, such as the secondcomposite surface preparation 96 b, may comprise cleaning 98 (see FIG. 4), such as the solvent wipe 100 (see FIG. 4 ), of the composite surface26 that has been abraded or sanded. As discussed above, the cleaning 98may be performed using a cloth or other suitable cleaning material. Thesolvent wipe 100 may include wiping with a solvent such as a methylpropyl ketone/methyl isobutyl ketone mixture, or another suitablesolvent or solvent mixture.

As shown in FIG. 4 , after the composite surface 26, that has beenabraded or sanded, optionally undergoes the composite surfacepreparation 96, such as the second composite surface preparation 96 b,the exemplary in-line process control check 92 further comprisescomposite surface measurement process check 106 using the one or moresurface analysis tools 60. As discussed above, the one or more surfaceanalysis tools 60 may include the FTIR spectrometer 66 (see FIG. 3 ),the OSEE sensor 70 (see FIG. 3 ), the gloss meter 74 (see FIG. 3 ), thecolorimeter 80 (see FIG. 3 ), and the optical interferometer 86 (seeFIG. 3 ). The one or more surface analysis tools 60 are used to takemeasurements 64 (see FIG. 3 ), such as test result measurements 64 a(see FIG. 3 ), of one or more abrasive surface preparation locations 44(see FIG. 3 ), such as one or more sanding surface preparation locations44 a (see FIG. 3 ), of the composite surface 26 (see FIG. 3 ) of thetest composite structure 28 a (see FIG. 3 ).

As shown in FIG. 4 , after the composite surface 26, that has beenabraded or sanded, undergoes the composite surface measurement processcheck 106 using the one or more surface analysis tools 60, the exemplaryin-line process control check 92 further comprises the post-processingoperation 50, such as bonding 52, painting 53, or another suitablepost-processing operation 50, if it is determined that the compositesurface 26 of the test composite structure 28 a is acceptable to proceedwith undergoing the post-processing operation 50. For example, thecomposite surface 26, if acceptable for bonding 52, may be bonded to astructure 40 (see FIG. 3 ), such as an aircraft structure 40 a (see FIG.3 ).

As shown in FIG. 4 , after the composite surface 26, that has beenacceptably abraded or sanded, undergoes the post-processing operation50, the exemplary in-line process control check 92 further comprises awitness coupon check 108 of the composite surface 26 of the testcomposite structure 28 a bonded to the structure 40 (see FIG. 3 ), suchas the aircraft structure 40 a (see FIG. 3 ), to verify that the bondedjoint is acceptable and meets certification requirements.

EXAMPLE

Each of the surface analysis tools 60, including the FTIR spectrometer66 (see FIGS. 3, 6 ), the OSEE sensor 70 (see FIGS. 3, 8 ), the glossmeter 74 (see FIGS. 3, 10 ), the colorimeter 80 (see FIGS. 3, 12 ), andthe optical interferometer 86 (see FIGS. 3, 14 ), were evaluated fortheir ability to quantitatively measure and assess the presence andlevel of abrasive surface preparation 42 (see FIG. 3 ), such as sandingsurface preparation 42 a (see FIG. 3 ). The surface analysis tools 60were selected based on their potential to detect variations in theabrasive surface preparation output, the tool's rapid measurementcapabilities, and the ability of their output to be used as a “go/no go”check in a real time process control system 90 c (see FIG. 3 ). The goalwas for each surface analysis tool 60 to be utilized as an in-lineprocess control check tool to verify if a bonding process step hadoccurred, and if it had been performed correctly.

In addition to analytical measurement, process parameters such assanding time, pressure, and equipment settings were also evaluated. Boththe surface analysis tool results and the process parameter variableswere intended to be integrated into the process control system 90 a (seeFIG. 3 ) discussed above, or an enhanced bonding workstation discussedbelow. A more tightly controlled process control system 90 a narrows thelimits in which an operation may take place and improves the reliabilityof the bonding process, resulting in a more robust bonded joint. Anadditional benefit of the in-line process control check 92 (see FIGS. 3,4 ) having video monitoring is a digital thread enabling downstreamtroubleshooting should an issue arise in the field on a specific bondedpart.

Composite Structure Fabrication

Composite structures 28 (see FIG. 3 ), such as composite substrates 34(see FIGS. 3, 4 ), in the form of composite panels 34 a (see FIGS. 3, 4), were made of carbon fiber epoxy composite fabric. The compositepanels were fabricated using 10 (ten) plies of 177° C. (350° F.) curecarbon fiber epoxy prepreg. The 8 (eight) inner plies wereunidirectional tape and the 2 (two) outer plies were fabric. Thecomposite panels were cured against a tool treated with FREKOTE 710-NCmold release agent (FREKOTE is a registered trademark owned by Henkel IP& Holding GMBH LLC of Germany.)

Composite Surface Preparation

The composite surface of each composite panel was solvent wiped priorto, and after, sanding, with an EASTMAN methyl isobutyl ketone(MIBK)/methyl propyl ketone (MPK) solvent mixture. (EASTMAN is aregistered trademark owned by Eastman Chemical Company of Kingsport,Tenn.) The composite panels were solvent wiped using cleaning cloths,meeting the requirements of SAE (Society of Automotive Engineers)International AMS3819C, Class 2, Grade A, “Cloths, Cleaning, forAircraft Primary and Secondary Structural Surfaces”.

Composite Surface Treatment

Each composite panel was surface treated by using varied processparameters associated with manually sanding with a random orbital sander(ROS) 104 a and 180 grit aluminum oxide sand paper disks. Time was usedas a processing variable. For assessment of the surface analysis tools60, including the FTIR spectrometer 66, the OSEE sensor 70, and theoptical interferometer 86, a ladder panel with various levels of sandingwas used, including the levels 56 (see FIG. 3 ) of the amount of sandingof: none (no sanding) 56 a, very very light 56 b, very light 56 c, light56 d, medium light 56 e, semi-full 56 f, and full 56 g (see FIGS. 5A-5B,7, and 13 ). For assessment of surface analysis tools 60, including thegloss meter 74 and the colorimeter 80, an array of composite panels wereutilized that had levels 57 (see FIG. 3 ) of sanding correlating to:none (no sanding) 57 a, 5-10 seconds 57 b, 10-20 second 57 c, 30 seconds57 d, and 1 minute (baseline) 57 e (see FIGS. 9, 11 ). Sanding for 1(one) minute was the control process baseline.

Composite Surface Analysis

Pre-bond composite surfaces were characterized before and aftercomposite surface treatment. The composite surfaces of the compositepanels were measured using Fourier transform infrared (FTIR) signalmeasurements 67 (see FIGS. 3, 5A-5B, 6 ), optically stimulated electronemission (OSEE) signal measurements 72 (see FIGS. 3, 7, 8 ), glossmeasurements 76 (see FIGS. 3, 9, 10 ), color values 82 (see FIGS. 3, 11,12 ), and roughness measurements 87 (see FIGS. 3, 13, 14 ). A KEYENCEVHX-2000 (Version 2.3.5.1) multi-scan digital microscope was used toimage each composite surface. (KEYENCE is a registered trademark ownedby Keyence Corporation of Osaka, Japan.) A polarizer and glare reductionsetting was used to accentuate surface morphology. Digital microscopeimages of the unsanded and sanded surfaces were collected at 20× and200×. Scratches were observed even on the non-sanded surface, indicatingthat they were likely from solvent wiping or composite panel handling. Adepth analysis of the 1 (one) minute sanded baseline composite panelconfirmed that the sanding surface preparation step generated a smoothedout surface with no detectable troughs or valleys.

FTIR

Fourier transform infrared (FTIR) signal measurements, includingchemical information measurements, were gathered using FTIRspectroscopy, with an AGILENT Model 4100 ExoScan spectrometer, gain of243, 64 scan, 8 cm⁻¹ wavenumber resolution between 650 and 4000wavenumbers and a diffuse reflectance attachment. (AGILENT is aregistered trademark owned by Agilent Technologies, Inc. of Santa Clara,Calif.) FIGS. 5A, 5B, and 6 relate to the FTIR analysis.

Now referring to FIG. 5A, FIG. 5A is an illustration of a graph 110showing Fourier transform infrared (FTIR) spectra plots 112 of a C—Hbonding region 114 of epoxy composite surfaces 26 c (see FIG. 3 ) atvarious levels 56 of an amount of sanding 48 a (see FIG. 3 ), based onFTIR signal measurements 67 (see FIG. 3 ) taken with the FTIRspectrometer 66 (see FIGS. 3, 6 ). As shown in FIG. 5A, the graph 110shows absorbance 116 on the y-axis, and shows wavenumbers (cm⁻¹) 118 onthe x-axis. Peak area analysis was performed in the C—H bonding region114, shown as the region between 3016 cm⁻¹ to 2785 cm⁻¹, representingthe C (carbon)— H (hydrogen) bonding region 114 of the epoxy polymer ofthe epoxy composite surface 26 c of the composite structure 28 (see FIG.3 ), such as the test composite structure 28 a (see FIG. 3 ). As shownin FIG. 5A, the levels 56 of the amount of sanding 48 a (see FIG. 3 )include: 1—NONE (no sanding) 56 a, 2—VERY VERY LIGHT 56 b, 3—VERY LIGHT56 c, 4—LIGHT 56 d, 5—MEDIUM LIGHT 56 e, 6—SEMI-FULL 56 f, and 7—FULL 56g. FIG. 5A further shows the FTIR spectra plots 112 numbered 1-7. Adecrease in the overall FTIR signal measurements 67 (see FIG. 3 ) wasobserved with increased sanding, potentially due to the reduction in theamount of organic epoxy resin on the surface, with increased sandingtime.

Now referring to FIG. 5B, FIG. 5B is an illustration of a graph 120showing a Fourier transform infrared (FTIR)C—H region peak area 122 ofepoxy composite surfaces 26 c (see FIG. 3 ) after sanding 48 a (see FIG.3 ). As shown in FIG. 5B, the graph 120 shows the FTIR C—H region peakarea 122 between 3016 cm⁻¹ to 2785 cm⁻¹ on the y-axis, and shows thelevels 56 of the amount of sanding 48 a on the x-axis. The epoxycomposite surfaces 26 c were sanded at the various levels 56 with arandom orbital sander (ROS) 104 a (see FIG. 4 ) having a 180 gritaluminum oxide sand paper. FIG. 5B shows plots 124 a-124 g of the FTIRC—H region peak area 122 versus level 56 of the amount of sanding 48 a.The results, as shown by the graph 120 (see FIG. 5B), indicated adecrease in FTIR C—H region peak area 122 versus level 56 of the amountof sanding 48 a. There was a high standard deviation and near overlap ofthe error bars in the lower sanded region. The results, as shown by thegraph 120, showed that there was potential for usage of FTIR for in-lineprocess control to indicate sanded or unsanded surfaces, and that FTIRwas able to successfully detect the level of abrasive surfacepreparation 42 (see FIG. 3 ), such as sanding surface preparation 42 a(see FIG. 3 ). Setting a target value 62 (see FIG. 3 ), such as an FTIRtarget value 62 a (see FIG. 3 ), or threshold limit, for the amount ofsanding and establishing whether the FTIR C—H region peak area 122selected had enough differentiation from the baseline values wasrecommended. The results showed that using the FTIR spectroscopy process68 (see FIG. 3 ) and the FTIR spectrometer 66 (see FIG. 6 ) detectedwhether the epoxy composite surface 26 c was sanded or unsanded, andalso detected the level of the sanding or sanding surface preparation.Although the the FTIR C—H region peak area 122 shown in FIG. 5B isbetween 3016 cm′ to 2785 cm′, another suitable range may also be used.Preferably, the FTIR C—H region peak area 122 is in a range between 3200cm′ to 2500 cm⁻¹. More preferably, the FTIR C—H region peak area 122 isin a range between 3100 cm⁻¹ to 2600 cm⁻¹. Most preferably, the FTIR C—Hregion peak area 122 is in a range between 3016 cm′ to 2785 cm⁻¹.

Now referring to FIG. 6 , FIG. 6 is an illustration of a perspectiveside view of a surface analysis tool 60, such as in the form of aFourier transform infrared (FTIR) spectrometer 66, in use by a user 125taking Fourier transform infrared (FTIR) signal measurements 67 (seeFIG. 3 ) of an abraded surface 49, such as a sanded surface 49 a, afterabrading 48 (see FIG. 3 ), such as sanding 48 a (see FIG. 3 ), atvarious levels 56. As shown in FIG. 6 , the FTIR spectrometer 66 detectsFTIR signal measurements 67 at the levels 56 of the amount of abrading48, such as sanding 48 a, of none (no sanding) 56 a, very very light 56b, very light 56 c, light 56 d, medium light 56 e, semi-full 56 f, andfull 56 g, of the composite surface 26, such as the test compositesurface 26 a, of the composite structure 28, such as the test compositestructure 28 a. As further shown in FIG. 6 , the surface analysis tool60, such as in the form of the FTIR spectrometer 66, is a portablesurface analysis tool 60 a that may be hand-held and manually used totake the FTIR signal measurements 67.

OSEE

Optically stimulated electron emission (OSEE) measurements were gatheredusing the optically stimulated electron emission (OSEE) sensor developedby NASA (National Aeronautics and Space Administration), as disclosed inU.S. Pat. No. 5,393,980. The OSEE measurements were taken using anultraviolet (UV) lamp set point of 3041, grid offset of −41 m, andpeak-to-peak amplitude of 3.7. FIGS. 7 and 8 relate to the OSEEanalysis.

Now referring to FIG. 7 , FIG. 7 is an illustration of a graph 126showing optically stimulated electron emission (OSEE) signalmeasurements 72 of epoxy composite surfaces 26 c (see FIG. 3 ) atvarious levels 56 of the amount of sanding 48 a (see FIG. 3 ), based onOSEE signal measurements 72 taken with an OSEE sensor 70 (see FIGS. 3, 8). As shown in FIG. 7 , the graph 126 shows the OSEE signal measurements72 on the y-axis, and shows the levels 56 of the amount of sanding 48 aon the x-axis. The epoxy composite surfaces 26 c were sanded at thevarious levels 56 with a random orbital sander (ROS) 104 a (see FIG. 4 )having a 180 grit aluminum oxide sand paper. FIG. 7 shows plots 128a-128 g of the OSEE signal measurements 72 versus the levels 56 of theamount of sanding 48 a.

The OSEE signal measurements 72 reached a leveling off point, which mayneed to be considered when using the OSEE sensor 70 on compositesubstrates made of composite materials different than epoxy compositematerials. The use of the OSEE sensor 70 also required compressed gas 73(see FIG. 3 ), such as compressed argon gas 73 a (see FIG. 3 ), tofunction, and there may be some sensitivity of the OSEE sensor 70 ordetector to frayed or exposed carbon fibers. However, the results, asshown by the graph 126, showed that OSEE was able to successfully detectthe level of abrasive surface preparation 42 (see FIG. 3 ), such assanding surface preparation 42 a (see FIG. 3 ), with good sensitivity,and showed that OSEE was able to successfully measure the presence andlevel of sanding 48 a in a rapid “go/no go” manner. The results showedthat using the OSEE sensor 70 (see FIG. 8 ) detected whether thecomposite surface was sanded or unsanded, and also detected the level ofthe sanding or sanding surface preparation.

Now referring to FIG. 8 , FIG. 8 is an illustration of a perspectiveside view of a surface analysis tool 60, such as in the form of anoptically stimulated electron emission (OSEE) sensor 70, in use by auser 125 taking optically stimulated electron emission (OSEE) signalmeasurements 72 of an abraded surface 49, such as a sanded surface 49 a,after abrading 48 (see FIG. 3 ), such as sanding 48 a (see FIG. 3 ), atvarious levels 56. As shown in FIG. 8 , the OSEE sensor 70 detects OSEEsignal measurements 72 at the levels 56 of the amount of abrading 48,such as sanding 48 a, of none (no sanding) 56 a, very very light 56 b,very light 56 c, light 56 d, medium light 56 e, semi-full 56 f, and full56 g, of the composite surface 26, such as the test composite surface 26a, of the composite structure 28, such as the test composite structure28 a. As further shown in FIG. 8 , the surface analysis tool 60, such asin the form of the OSEE sensor 70, is a portable surface analysis tool60 a that may be hand-held and manually used to take the OSEE signalmeasurements 72.

Gloss

Gloss measurements for all but the gloss D65/10 were collected using aBYK GARDNER Micro-Tri-Gloss Model 4435 gloss meter. Gloss measurementsfor gloss D65/10 were collected using a BYK GARDNER Spectro-Guide 45/0gloss Model CC-6801 color meter, separate from the gloss meter. (BYKGARDNER is a registered trademark owned by BYK Gardner GmbH of Germany.)For gloss D65/10, D65 is an illuminant which represents standarddaylight, and 10 refers to a gloss aperture which is 5×10 mm (glossvalue reported by the color meter had an illumination angle geometry of60 degrees). FIGS. 9 and 10 relate to the gloss analysis.

Now referring to FIG. 9 , FIG. 9 is an illustration of a graph 130showing gloss individual maximums 132 of epoxy composite surfaces 26 c(see FIG. 3 ) at various levels 57 of a time of sanding 48 a (see FIG. 3), based on gloss measurements 76 (see FIG. 3 ) taken with a gloss meter74 (see FIGS. 3, 10 ). Gloss 77 (see FIG. 3 ) was investigated toquantitatively assess a level 57 (see FIG. 9 ) of the time of sanding 48a (see FIG. 3 ), which was detected visually. As shown in FIG. 9 , thegraph 130 shows gloss units 134 of the gloss individual maximums 132 onthe y-axis, and shows various levels 57 of the time of sanding 48 a fora gloss D65/10 individual maximum 132 a, a gloss 20 (twenty) degreeindividual maximum 132 b, a gloss 60 (sixty) degree individual maximum132 c, and a gloss 85 (eighty-five) degree individual maximum 132 d, onthe x-axis. The epoxy composite surfaces 26 c were sanded at the variouslevels 57 with a random orbital sander (ROS) 104 a (see FIG. 4 ) havinga 180 grit aluminum oxide sand paper. Gloss measurements 76 (see FIG. 3) in gloss units 134 (see FIG. 9 ) of sanded surfaces 49 a (see FIG. 3), were collected at gloss individual maximums 132 of D65/10, 20 degrees(20 degree gloss illumination angle geometry 78 c (see FIG. 3 )), 60degrees (60 degree gloss illumination angle geometry 78 b (see FIG. 3)), and 85 degrees (85 degree gloss illumination angle geometry 78 a(see FIG. 3 )).

As shown in FIG. 9 , the levels 57 of the time of sanding 48 a (see FIG.3 ) include: NONE (no sanding) 57 a, 5-10 SECONDS 57 b, 10-20 SECONDS 57c, 30 SECONDS 57 d, and 1 MINUTE (BASELINE) 57 e. FIG. 9 shows plots 136a-136 e for the gloss D65/10 individual maximum 132 a at the variouslevels 57. FIG. 9 shows plots 138 a-138 e for the gloss 20 (twenty)degree individual maximum 132 b at the various levels 57. FIG. 9 showsplots 140 a-140 e for the gloss 60 (sixty) degree individual maximum 132c at the various levels 57. FIG. 9 shows plots 142 a-142 e for the gloss85 (eighty-five) degree individual maximum 132 d at the various levels57.

The results, as shown by the graph 130, showed that the glossmeasurements 76 (see FIG. 3 ) detected whether the composite surface 26(see FIG. 3 ) was sanded or unsanded. The gloss 85 (eighty-five) degreeindividual maximum 132 d showed correlation to the levels 57 of the timeof sanding 48 a. Gloss at 85 (eighty-five) degrees was the recommendedgeometry for low gloss, matte surfaces. Minimal post signal processing69 (see FIG. 3 ) was required. The results showed that using the glossmeter 74 (see FIG. 10 ) at the 85 (eighty-five) degree glossillumination angle geometry 78 a (see FIG. 3 ) detected whether thecomposite surface was sanded or unsanded, and also detected the level ofthe sanding or sanding surface preparation.

Now referring to FIG. 10 , FIG. 10 is an illustration of a perspectiveside view of a surface analysis tool 60, such as in the form of a glossmeter 74, in use by a user 125 taking a gloss measurement 76 of anabraded surface 49, such as a sanded surface 49 a, after abrading 48(see FIG. 3 ), such as sanding 48 a (see FIG. 3 ), of the compositesurface 26, such as the test composite surface 26 a, of the compositestructure 28, such as the test composite structure 28 a. As shown inFIG. 10 , the surface analysis tool 60, such as in the form of the glossmeter 74, is a portable surface analysis tool 60 a that may be hand-heldand manually used to take the gloss measurements 76.

Color

Color values were taken using a BYK GARDNER spectro-guide 45/0 glossModel CC-6801 using a Commission Internationale de 1′Elcairage (CIE) Labcolor scale. (BYK GARDNER is a registered trademark owned by BYK GardnerGmbH of Germany.) FIGS. 11 and 12 relate to the color analysis.

Now referring to FIG. 11 , FIG. 11 is an illustration of a graph 144showing delta color values individual maximums 146 of epoxy compositesurfaces 26 c (see FIG. 3 ), after sanding 48 a (see FIG. 3 ), atvarious levels 57 of the time of sanding 48 a, based on delta colorvalues 84 (see FIG. 3 ) measured with a colorimeter 80 (see FIGS. 3, 12). Sanded and unsanded surfaces were distinguished from one anotherusing L* values. L* value is measurement of “Luminance” (lightness) in aCIE color scheme (a and b are color scales). Direct color measurementdid not detect the level of sanding. When a delta E* (ΔE*) color value84 a (see FIG. 3 ) and a delta L* (ΔL*) color value 84 b (see FIG. 3 )were calculated, as a difference from the baseline control, and thedelta L* (ΔL*) color value individual maximum 146 a (see FIG. 11 ) andthe delta E* (ΔE*) color value individual maximum 146 b were collected,there was a correlation to levels 57 (see FIG. 11 ) of sanding.

As shown in FIG. 11 , the graph 144 shows color units 148 of the deltacolor values (ΔL*, ΔE*) individual maximums 146 on the y-axis, and showsvarious levels 57 of the time of sanding 48 a for a delta L* (ΔL*) colorvalue individual maximum 146 a, and for a delta E* (ΔE*) color valueindividual maximum 146 b. The epoxy composite surfaces 26 c were sandedat the various levels 57 with a random orbital sander (ROS) 104 a (seeFIG. 4 ) having a 180 grit aluminum oxide sand paper. As shown in FIG.10 , the levels 57 of the time of sanding 48 a (see FIG. 3 ) include:NONE (no sanding) 57 a, 5-10 SECONDS 57 b, 10-20 SECONDS 57 c, 30SECONDS 57 d, and 1 MINUTE (BASELINE) 57 e. FIG. 10 shows plots 150a-150 e for the delta L* (ΔL*) color value individual maximum 146 a atthe various levels 57. FIG. 10 shows plots 152 a-152 e for the delta E*(ΔE*) color value individual maximum 146 b at the various levels 57.

The results, as shown by the graph 144, showed that both the delta L*(ΔL*) color value individual maximum 146 a and the delta E* (ΔE*) colorvalue individual maximum 146 b were good candidates to be used as aquality control tool for the in-line process control check 92 (see FIG.3 ), or monitoring, with the system 90 (see FIG. 3 ), such as theprocess control system 90 a (see FIG. 3 ), for example, the bond processcontrol system 90 b (see FIG. 3 ). Minimal post signal processing 69(see FIG. 3 ) was required. The results showed that using thecolorimeter 80 and the delta E* (ΔE*) color value individual maximum 146b detected whether the composite surface was sanded or unsanded, andalso detected the level of the sanding or sanding surface preparation.

Now referring to FIG. 12 , FIG. 12 is an illustration of a perspectivetop view of a surface analysis tool 60, such as in the form of acolorimeter 80, in use by a user 125 measuring color values 82 of anabraded surface 49, such as a sanded surface 49 a, after abrading 48(see FIG. 3 ), such as sanding 48 a (see FIG. 3 ), of the compositesurface 26, such as the test composite surface 26 a, of the compositestructure 28, such as the test composite structure 28 a. As shown inFIG. 12 , the surface analysis tool 60, such as in the form of thecolorimeter 80, is a portable surface analysis tool 60 a that may behand-held and manually used to measure the color values 82.

Roughness

Roughness (Ra and Rz) measurements were taken using an opticalinterferometer with white visible light. The optical interferometer usedwas a WYKO NT2000 (Veeco) Surface Profiler (WYKO is a registeredtrademark owned by Bruker Nano, Inc. of Santa Barbara, Calif.) FIGS. 13and 14 relate to the roughness analysis.

Now referring to FIG. 13 , FIG. 13 is an illustration of a graph 154showing a roughness measurement distribution 156 of roughnessmeasurement plots 158 of epoxy composite surfaces 26 c (see FIG. 3 ) atvarious levels 56 of the amount of sanding 48 a (see FIG. 3 ), based onroughness measurements 87 measured with an optical interferometer 86(see FIGS. 3, 14 ). As shown in FIG. 13 , the graph 154 shows number ofdata points 160 on the y-axis, and shows roughness measurements 87 onthe x-axis. As further shown in FIG. 13 , the levels 56 of the amount ofsanding 48 a (see FIG. 3 ) include: 1—NONE (no sanding) 56 a, 2—VERYVERY LIGHT 56 b, 3—VERY LIGHT 56 c, 4—LIGHT 56 d, 5—MEDIUM LIGHT 56 e,6—SEMI-FULL 56 f, and 7—FULL 56 g. FIG. 13 further shows the roughnessmeasurement plots 158 numbered 1-7.

The results, as shown by the graph 154, showed that roughnessmeasurements 87 measured with the optical interferometer 86 (see FIG. 3) had the ability to detect the level 56 of the amount of sanding 48 a,including composite surface treatment 102 (see FIG. 4 ). In addition,the results, as shown by the graph 154, showed that the curves of theroughness measurement plots 158 were more Gaussian with a greaterhomogeneous sanded surface. Use of the optical interferometer 86 tomeasure the roughness 88 (see FIG. 3 ) also required significant postsignal processing 69 (see FIG. 3 ) and a slight qualitative assessmentof the results. The results showed that using the optical interferometer86 detected whether the composite surface was sanded or unsanded, andalso detected the level of the sanding or sanding surface preparation.

Now referring to FIG. 14 , FIG. 14 is an illustration of a perspectivefront view of a surface analysis tool 60, such as in the form of anoptical interferometer 86, taking roughness measurements 87 of anabraded surface 49, such as a sanded surface 49 a, after abrading 48(see FIG. 3 ), such as sanding 48 a (see FIG. 3 ), of the compositesurface 26, such as the test composite surface 26 a, of the compositestructure 28, such as the test composite structure 28 a. As shown inFIG. 14 , the surface analysis tool 60, such as in the form of theoptical interferometer 86, is a portable surface analysis tool 60 a thatmay be easily moved and manually used to collect the roughnessmeasurements 87.

SUMMARY

The results identified five different surface analysis tools 60—the FTIRspectrometer 66 (see FIGS. 3, 6 ), the OSEE sensor 70 (see FIGS. 3, 8 ),the gloss meter 74 (see FIGS. 3, 10 ), the colorimeter 80 (see FIGS. 3,12 ), and the optical interferometer 86 (see FIGS. 3, 14 ), that wereused to set target values 62 (see FIG. 3 ), or threshold limits, forabrasive surface preparation 42 (see FIG. 3 ), such as sanding surfacepreparation 42 a (see FIG. 3 ), with manual sanding 48 b (see FIG. 3 ),using an abrading device 104 (see FIG. 3 ), such as a random orbitalsander 104 a (see FIG. 3 ). The results showed that the use of each ofthese surface analysis tools 60 successfully detected whether thecomposite surface was sanded or unsanded, and also successfully detectedthe level of the sanding or sanding surface preparation. These surfaceanalysis tools 60 defined the operating window and narrowed the limitson sanding parameters. Utilization of these surface analysis tools 60enables better process control, resulting in robust and reliablebonding.

Now referring to FIG. 15 , FIG. 15 is an illustration of a graph 162 ofan exemplary bond process flow time monitoring 164 showing an out ofprocess condition 166, in the form of a defect—under sanded panel 174.Tracking process flow time is another method of assessing bond processreliability and consistency. If a process step falls outside the normal,known flow time, it is flagged. An example of an output from the bondprocess flow time monitoring 164 is shown in FIG. 15 , where theidentification of a defect—under sanded panel 174 is made.

As shown in FIG. 15 , the graph 162 shows time 168 on the y-axis, andshows steps 170 of the exemplary bond process flow time monitoring 164on the x-axis. As further shown in FIG. 15 , the steps 170 include step1-check gloves 170 a, step 2-check solvent 170 b, step 3—apply solventto wiper 170 c, step 4—solvent wipe panel 170 d, step 5—check sandingdiscs 170 e, step 6-random orbital sand panel 170 f, step 7—applysolvent to wiper 170 g, step 8—solvent wipe panel 170 h, and step9—measure surface-process check 170 i. As further shown in FIG. 15 ,each step 170 is designed to include a baseline 172, and designed toinclude a time check 173 that should meet, or be equal to, the baseline172. For example, as shown in FIG. 15 , step 1-check gloves 170 aincludes a baseline plot 176 a and a time check plot 176 b that areequal; step 2-check solvent 170 b includes a baseline plot 178 a and atime check plot 178 b that are equal; step 3—apply solvent to wiper 170c includes a baseline plot 180 a and a time check plot 180 b that areequal; step 4—solvent wipe panel 170 d includes a baseline plot 182 aand a time check plot 182 b that are equal; step 5—check sanding discs170 e includes a baseline plot 184 a and a time check plot 184 b thatare equal; step 7—apply solvent to wiper 170 g includes a baseline plot188 a and a time check plot 188 b that are equal; step 8—solvent wipepanel 170 h includes a baseline plot 190 a and a time check plot 190 bthat are equal; and step 9—measure surface-process check 170 i includesa baseline plot 192 a and a time check plot 192 b that are equal.However, as shown by FIG. 15 , step 6-random orbital sand panel 170 fincludes a baseline plot 186 a that is not the same as, or equal to, aplot 186 b which indicates the defect—under sanded panel 174 and is theout of process condition 166.

The measurements 64 (see FIG. 3 ), such as the test result measurements64 a (see FIG. 3 ) of the surface analysis tools 60 used in the method10 (see FIG. 1 ), the quantitative method 10 a (see FIG. 2 ), and thesystem 90 (see FIG. 3 ), discussed above, provide for a go/no go processtool after the abrasive surface preparation 42 (see FIG. 3 ), such asthe sanding surface preparation 42 a (see FIG. 3 ), of the compositesurface 26 (see FIG. 3 ), such as the test composite surface 26 a (seeFIG. 3 ). The pre-bond surface check of the composite surface 26, withthe surface analysis tools 60, may be incorporated into an opticallyenhanced bonding workstation, or, for example, may be incorporated intoa method of monitoring and verifying a manufacturing process, asdisclosed in U.S. Pat. No. 9,591,273, the content of which is herebyincorporated by reference in its entirety.

Preferably, the surface analysis tools 60 (see FIG. 3 ) and themonitoring outputs of the surface analysis tools 60 are integrated intothe process control system 90 a (see FIG. 3 ). The intent of thestepwise bond process control development is its implementation in theactual production of bonded parts, for example, the optically enhancedbonding work station. The functionality of the system 90 (see FIG. 3 )includes process flow time monitoring, documentation of the processsteps, as well as in-line process checks.

Now referring to FIG. 16 , FIG. 16 is an illustration of a perspectiveview of an air vehicle 200, such as in the form of aircraft 200 a, thatincorporates one or more parts 218, such as one or more bonded parts220, manufactured using an exemplary version of an in-line processcontrol check 92 (see FIG. 4 ) of the disclosure.

As shown in FIG. 16 , the air vehicle 200, such as in the form ofaircraft 200 a, comprises a fuselage 202, a nose 204, a cockpit 206,wings 208, engines 210, and an empennage 212 comprising a verticalstabilizer 214 and horizontal stabilizers 216. The air vehicle 200 (seeFIG. 16 ), such as in the form of aircraft 200 a (see FIG. 16 ),comprises one or more parts 218, such as the one or more bonded parts220, installed within the aircraft 200 a, or alternatively, installed inthe engines 210, the wings 208, the empennage 212, or other suitableareas of the aircraft 200 a.

Now referring to FIGS. 17 and 18 , FIG. 17 is an illustration of a flowdiagram of an exemplary aircraft manufacturing and service method 300,and FIG. 18 is an illustration of an exemplary block diagram of anaircraft 316. Referring to FIGS. 17 and 18 , versions of the disclosuremay be described in the context of the aircraft manufacturing andservice method 300 as shown in FIG. 17 , and the aircraft 316 as shownin FIG. 18 .

During pre-production, exemplary aircraft manufacturing and servicemethod 300 may include specification and design 302 of the aircraft 316and material procurement 304. During manufacturing, component andsubassembly manufacturing 306 and system integration 308 of the aircraft316 takes place. Thereafter, the aircraft 316 may go throughcertification and delivery 310 in order to be placed in service 312.While in service 312 by a customer, the aircraft 316 may be scheduledfor routine maintenance and service 314 (which may also includemodification, reconfiguration, refurbishment, and other suitableservices).

Each of the processes of the aircraft manufacturing and service method300 may be performed or carried out by a system integrator, a thirdparty, and/or an operator (e.g., a customer). For the purposes of thisdescription, a system integrator may include, without limitation, anynumber of aircraft manufacturers and major-system subcontractors. Athird party may include, without limitation, any number of vendors,subcontractors, and suppliers. An operator may include an airline,leasing company, military entity, service organization, and othersuitable operators.

As shown in FIG. 18 , the aircraft 316 produced by the exemplaryaircraft manufacturing and service method 300 may include an airframe318 with a plurality of systems 320 and an interior 322. Examples of theplurality of systems 320 may include one or more of a propulsion system324, an electrical system 326, a hydraulic system 328, and anenvironmental system 330. Any number of other systems may be included.Although an aerospace example is shown, the principles of the disclosuremay be applied to other industries, such as the automotive industry.

Methods and systems embodied herein may be employed during any one ormore of the stages of the aircraft manufacturing and service method 300.For example, components or subassemblies corresponding to component andsubassembly manufacturing 306 may be fabricated or manufactured in amanner similar to components or subassemblies produced while theaircraft 316 is in service 312. Also, one or more apparatus embodiments,method embodiments, or a combination thereof, may be utilized duringcomponent and subassembly manufacturing 306 and system integration 308,for example, by substantially expediting assembly of or reducing thecost of the aircraft 316. Similarly, one or more of apparatusembodiments, method embodiments, or a combination thereof, may beutilized while the aircraft 316 is in service 312, for example andwithout limitation, to maintenance and service 314.

Disclosed versions of the method 10 (see FIG. 1 ), the quantitativemethod 10 a (see FIG. 2 ), and the system 90 (see FIG. 3 ) provide forthe detection of a level 55, such as a test result level 58 (see FIG. 3) of abrasive surface preparation 42 (see FIG. 3 ), such as sandingsurface preparation 42 a (see FIG. 3 ), grit blasting surfacepreparation, nylon pad abrasive surface preparation, or another suitableabrasive surface preparation with an abrasive media tool that physicallyabrades the composite surface 26 (see FIG. 3 ), to prevent under sandingor over sanding of the composite surface 26, prior to a post-processingoperation 50 (see FIG. 3 ), such as bonding 52 (see FIG. 3 ) or painting53 (see FIG. 3 ), and to result in robust, consistent, and reliablebonding 52 or painting 53, such as adhesion painting, through processcontrol. A series of portable, pre-bond surface analysis tools 60,including the FTIR spectrometer 66 (see FIGS. 3, 6 ), the OSEE sensor 70(see FIGS. 3, 8 ), the gloss meter 74 (see FIGS. 3, 10 ), thecolorimeter 80 (see FIGS. 3, 12 ), and the optical interferometer 86(see FIGS. 3, 14 ), may be used for in-line bond process control ofabrading 48 (see FIG. 3 ), such as sanding 48 a, of composite surfaces26, such as epoxy composite surfaces 26 c (see FIG. 3 ). The surfaceanalysis tools 60 detect target values 62 (see FIG. 3 ), or thresholdlimits, for a plurality of levels 55 (see FIG. 3 ) of abrasive surfacepreparation 42 (see FIG. 3 ), such as sanding surface preparation 42 a(see FIG. 3 ), using Fourier transform infrared spectroscopy (FTIR),optically stimulated electron emissions (OSEE), gloss, color, androughness analysis of composite surfaces 26 (see FIG. 3 ) that have beenabraded 48 (see FIG. 3 ) or sanded 48 a (see FIG. 3 ).

In addition, disclosed versions of the method 10 (see FIG. 1 ), thequantitative method 10 a (see FIG. 2 ), and the system 90 (see FIG. 3 )provide for the use of surface analysis tools 60, including the FTIRspectrometer 66 (see FIGS. 3, 6 ), the OSEE sensor 70 (see FIGS. 3, 8 ),the gloss meter 74 (see FIGS. 3, 10 ), the colorimeter 80 (see FIGS. 3,12 ), and the optical interferometer 86 (see FIGS. 3, 14 ), in a qualityassurance methodology, or for incorporation into an optically enhancedbonding workstation. Quantitative measurement of abrasive surfacepreparation 42 (see FIG. 3 ), such as sanding surface preparation 42 a(see FIG. 3 ), grit blasting surface preparation, nylon pad abrasivesurface preparation, or another suitable abrasive surface preparationwith an abrasive media tool that physically abrades the compositesurface 26 (see FIG. 3 ) ensures the quality 24 (see FIG. 3 ) ofsubsequent adhesive bonding of the composite surface 26 to anotherstructure 40 (see FIG. 3 ), such as an aircraft structure 40 a (see FIG.3 ).

Moreover, disclosed versions of the method 10 (see FIG. 1 ), thequantitative method 10 a (see FIG. 2 ), and the system 90 (see FIG. 3 )may provide a reduced variability in abrasive surface preparation 42methods, to produce robust bonded joints and robust bonded parts 220(see FIG. 16 ), and to promote reliable adhesion, and to ensure that thecomposite surface 26 (see FIG. 3 ) has been properly prepared before thepost-processing operation 50 (see FIG. 3 ), such as bonding 52 (see FIG.3 ) or painting 53 (see FIG. 3 ). Further, disclosed versions of themethod 10 (see FIG. 1 ), the quantitative method 10 a (see FIG. 2 ), andthe system 90 (see FIG. 3 ) may mitigate any risks associated with bondprocessing through an in-line bond process monitoring system, and maydefine the processing window and control the fabrication steps to ensurea repeatable, reliable, and consistent bonding process, and define thequantitative outputs from the surface analysis tool measurements andoutputs for integration into the process control system 90 a (see FIG. 3) as “go/no go” process checks. The intention of the in-line processcontrol check 92 (see FIG. 3 ) is definition and control of processlimits, resulting in consistent and reliable production of robust bonds.Disclosed versions of the method 10 (see FIG. 1 ), the quantitativemethod 10 a (see FIG. 2 ), and the system 90 (see FIG. 3 ) provide aframework on how to carry out implementation of bond process control.

In addition, disclosed versions of the method 10 (see FIG. 1 ), thequantitative method 10 a (see FIG. 2 ), and the system 90 (see FIG. 3 )provide a framework for implementation of bond process control on anybonding system and ultimately allow for certification of robust bondedstructures and bonded parts 220 (see FIG. 16 ) and safeguard the qualityof aircraft structural adhesive bonds. Any aerospace manufacturer, orother manufacturer, such as an automotive manufacturer, that utilizesabrading, sanding, grit blasting, nylon pad abrasive surfacepreparation, or another suitable abrasive surface preparation ofcomposite surfaces may have the ability to utilize disclosed versions ofthe method 10 (see FIG. 1 ), the quantitative method 10 a (see FIG. 2 ),and the system 90 (see FIG. 3 ). Disclosed versions of the method 10(see FIG. 1 ), the quantitative method 10 a (see FIG. 2 ), and thesystem 90 (see FIG. 3 ) may enable rapid certification of bondedstructures and bonded parts 220 (see FIG. 16 ) by validating robust andreliable bond processing, such as aircraft structural adhesive bondprocessing, prior to launching certification testing. Further, disclosedversions of the method 10 (see FIG. 1 ), the quantitative method 10 a(see FIG. 2 ), and the system 90 (see FIG. 3 ) provide an approach thatmay be used to verify or certify the integrity of structural bonds forvarious applications, such as transportation applications, includingaircraft, automotive, and water craft; architectural, includingbuildings and bridges; and other suitable applications requiringverification or certification of the integrity of structural bonds.

Many modifications and other versions of the disclosure will come tomind to one skilled in the art to which this disclosure pertains havingthe benefit of the teachings presented in the foregoing descriptions andthe associated drawings. The versions described herein are meant to beillustrative and are not intended to be limiting or exhaustive. Althoughspecific terms are employed herein, they are used in a generic anddescriptive sense only and not for purposes of limitation.

What is claimed is:
 1. A quantitative method for determining a level ofa sanding surface preparation of a carbon fiber composite surface, priorto the carbon fiber composite surface undergoing a post-processingoperation, the quantitative method comprising: fabricating a ladderpanel of a plurality of levels of sanding correlating to an amount ofsanding of sanding surface preparation standards for a reference carbonfiber composite surface of one or more reference carbon fiber compositestructures; using one or more surface analysis tools comprising one of,a Fourier transform infrared (FTIR) spectrometer, an opticallystimulated electron emission (OSEE) sensor, or an opticalinterferometer, to create one or more target values for quantifying eachof the plurality of levels of sanding of the sanding surface preparationstandards; measuring, with the one or more surface analysis tools, oneor more sanding surface preparation locations on the carbon fibercomposite surface of a test carbon fiber composite structure, to obtainone or more test result measurements; comparing each of the one or moretest result measurements to the plurality of levels of sanding of thesanding surface preparation standards, to obtain one or more test resultlevels of the sanding surface preparation of the test carbon fibercomposite structure; determining if the one or more test result levelsof the sanding surface preparation meet the one or more target values,to determine whether the carbon fiber composite surface is sanded orunsanded, and to determine the level of sanding correlating to theamount of sanding of the sanding surface preparation of the carbon fibercomposite surface; and determining whether the carbon fiber compositesurface of the test carbon fiber composite structure is acceptable toproceed with undergoing the post-processing operation.
 2. Thequantitative method of claim 1, wherein fabricating the ladder panel ofthe plurality of levels of sanding further comprises, fabricating theladder panel of the plurality of levels of sanding correlating to theamount of sanding, the plurality of levels of sanding comprising, nosanding, very very light sanding, very light sanding, light sanding,medium light sanding, semi-full sanding, and full sanding.
 3. Thequantitative method of claim 1, wherein using the one or more surfaceanalysis tools further comprises, manually using the one or more surfaceanalysis tools comprising portable surface analysis tools that arehand-held.
 4. The quantitative method of claim 1, wherein measuring,with the one or more surface analysis tools, further comprises,measuring with the Fourier transform infrared (FTIR) spectrometer, tomeasure one or more Fourier transform infrared (FTIR) signalmeasurements of the one or more sanding surface preparation locations onthe carbon fiber composite surface, to obtain an infrared (IR) spectraof absorption or emission of the one or more sanding surface preparationlocations of the carbon fiber composite surface of the test carbon fibercomposite structure.
 5. The quantitative method of claim 1, whereinmeasuring, with the one or more surface analysis tools, furthercomprises, measuring with the Fourier transform infrared (FTIR)spectrometer, to expose the one or more sanding surface preparationlocations on the carbon fiber composite surface to an infrared (IR)light source that is reflected onto a detector that measures an amountof light absorbed by the one or more sanding surface preparationlocations on the carbon fiber composite surface, to detect the one ormore test result levels of the sanding surface preparation of the testcarbon fiber composite structure.
 6. The quantitative method of claim 1,wherein measuring, with the one or more surface analysis tools, furthercomprises, measuring with the optically stimulated electron emission(OSEE) sensor, to measure one or more optically stimulated electronemission (OSEE) signal measurements of the one or more sanding surfacepreparation locations on the carbon fiber composite surface, by usingultraviolet (UV) light to create electron emission from the one or moresanding surface preparation locations on the carbon fiber compositesurface.
 7. The quantitative method of claim 1, wherein measuring, withthe one or more surface analysis tools, further comprises, measuringwith the optically stimulated electron emission (OSEE) sensor, where theOSEE sensor uses compressed gas comprising compressed argon gas.
 8. Thequantitative method of claim 1, wherein measuring, with the one or moresurface analysis tools, further comprises, measuring with the opticalinterferometer, to measure one or more roughness measurements of the oneor more sanding surface preparation locations on the carbon fibercomposite surface, the one or more roughness measurements comprising oneor more of, arithmetical mean roughness, and mean roughness depth. 9.The quantitative method of claim 1, wherein determining whether thecarbon fiber composite surface of the test carbon fiber compositestructure is acceptable to proceed with undergoing the post-processingoperation further comprises, determining whether the carbon fibercomposite surface is acceptable to proceed with undergoing thepost-processing operation comprising one or more of: bonding the carbonfiber composite surface to a structure, the bonding comprising one of,paste bonding, or adhesive bonding; and painting the carbon fibercomposite surface with a paint.
 10. The quantitative method of claim 1,wherein using the one or more surface analysis tools further comprises,using the one or more surface analysis tools as an in-line processcontrol check in a real time process control system, to provide apre-bond surface check of the carbon fiber composite surface of the testcarbon fiber composite structure.
 11. A quantitative method fordetermining a level of a sanding surface preparation of a carbon fibercomposite surface, prior to bonding the carbon fiber composite surfaceto an aircraft composite structure, the quantitative method comprising:fabricating a ladder panel of a plurality of levels of sandingcorrelating to an amount of sanding of sanding surface preparationstandards for a reference carbon fiber composite surface of one or morereference carbon fiber composite structures; using one or more surfaceanalysis tools to create one or more target values for quantifying eachof the plurality of levels of sanding of the sanding surface preparationstandards, wherein the one or more surface analysis tools comprise oneof, a Fourier transform infrared (FTIR) spectrometer, an opticallystimulated electron emission (OSEE) sensor, or an opticalinterferometer; measuring, with the one or more surface analysis tools,one or more sanding surface preparation locations on the carbon fibercomposite surface of a test carbon fiber composite structure, to obtainone or more test result measurements; comparing each of the one or moretest result measurements to the plurality of levels of sanding of thesanding surface preparation standards, to obtain one or more test resultlevels of the sanding surface preparation of the test carbon fibercomposite structure; determining if the one or more test result levelsof the sanding surface preparation meet the one or more target values,to determine whether the carbon fiber composite surface is sanded orunsanded, and to determine the level of sanding correlating to theamount of sanding of the sanding surface preparation of the carbon fibercomposite surface; and determining whether the carbon fiber compositesurface of the test carbon fiber composite structure is acceptable toproceed with bonding to the aircraft composite structure.
 12. Thequantitative method of claim 11, wherein measuring, with the one or moresurface analysis tools, further comprises, measuring with the Fouriertransform infrared (FTIR) spectrometer, to measure one or more Fouriertransform infrared (FTIR) signal measurements of the one or more sandingsurface preparation locations on the carbon fiber composite surface, toobtain an infrared (IR) spectra of absorption or emission of the one ormore sanding surface preparation locations of the carbon fiber compositesurface of the test carbon fiber composite structure.
 13. Thequantitative method of claim 11, wherein measuring, with the one or moresurface analysis tools, further comprises, measuring with the opticallystimulated electron emission (OSEE) sensor, to measure one or moreoptically stimulated electron emission (OSEE) signal measurements of theone or more sanding surface preparation locations on the carbon fibercomposite surface, by using ultraviolet (UV) light to create electronemission from the one or more sanding surface preparation locations onthe carbon fiber composite surface.
 14. The quantitative method of claim11, wherein measuring, with the one or more surface analysis tools,further comprises, measuring with the optical interferometer, to measureone or more roughness measurements of the one or more sanding surfacepreparation locations on the carbon fiber composite surface, the one ormore roughness measurements comprising one or more of, arithmetical meanroughness, and mean roughness depth.
 15. A quantitative system fordetermining a level of a sanding surface preparation of a carbon fibercomposite surface, prior to the carbon fiber composite surfaceundergoing a post-processing operation, the quantitative systemcomprising: one or more reference carbon fiber composite structureshaving a reference carbon fiber composite surface; a ladder panel of aplurality of levels of sanding correlating to an amount of sanding ofsanding surface preparation standards fabricated for the referencecarbon fiber composite surface; a test carbon fiber composite structurehaving the carbon fiber composite surface, and the carbon fibercomposite surface having one or more sanding surface preparationlocations that have been sanded with an abrading device; and one or moresurface analysis tools comprising one of, a Fourier transform infrared(FTIR) spectrometer, an optically stimulated electron emission (OSEE)sensor, or an optical interferometer, to create one or more targetvalues for quantifying each of the plurality of levels of the sandingsurface preparation standards, and the one or more surface analysistools configured to measure the one or more sanding surface preparationlocations, to obtain one or more test result measurements, wherein eachof the one or more test result measurements is compared to the pluralityof levels of sanding of the sanding surface preparation standards, toobtain one or more test result levels of the sanding surface preparationof the test carbon fiber composite structure, and to determine if theone or more test result levels meet the one or more target values, todetermine whether the carbon fiber composite surface is sanded orunsanded, and to determine the levels of sanding correlating to theamount of sanding of the sanding surface preparation of the carbon fibercomposite surface, and to determine if the carbon fiber compositesurface is acceptable to proceed with undergoing the post-processingoperation.
 16. The quantitative system of claim 15, wherein the Fouriertransform infrared (FTIR) spectrometer measures one or more Fouriertransform infrared (FTIR) signal measurements of the one or more sandingsurface preparation locations on the carbon fiber composite surface, toobtain an infrared (IR) spectra of absorption or emission of the one ormore sanding surface preparation locations of the carbon fiber compositesurface of the test carbon fiber composite structure.
 17. Thequantitative system of claim 15, wherein the optically stimulatedelectron emission (OSEE) sensor measures one or more opticallystimulated electron emission (OSEE) signal measurements of the carbonfiber composite surface, by using ultraviolet (UV) light to createelectron emission from the one or more sanding surface preparationlocations on the carbon fiber composite surface.
 18. The quantitativesystem of claim 15, wherein the optical interferometer measures one ormore roughness measurements of the one or more sanding surfacepreparation locations on the carbon fiber composite surface, the one ormore roughness measurements comprising one or more of, arithmetical meanroughness, and mean roughness depth.
 19. The quantitative system ofclaim 15, wherein the abrading device comprises a random orbital sanderhaving a 180 grit aluminum oxide sand paper.
 20. The quantitative systemof claim 15, wherein the test carbon fiber composite structure comprisesa carbon fiber epoxy composite panel.